When a guerrila movement has the backing of the people, it'd be unbeatable. Without, it can work, but it's beatable. You can't kill eeveryone.
-Tamil Tigers.
-Korean resistance to Imperial Japan.
-French Resistance in WWII
-Spanish Resistance to Napoleon
-Venetian and Milano resistance to Austrian rule
-Balklands resistance to the Ottoman Empire
-"Indian Wars" in the United States
-Czeck revolution in the 50's
-Finland in the Winter War
-Ethiopian resistance to Italy
-The Jewish rebellion in 70 A.D.
-Athenian revolt to the Macedonian Empire
-The Peasants Rebellion in England in 11th century
-The Easter Rising
-O'Neils rebellion in the 17th century
-Sunni rebellions in Iraq in post Gulf War 1
Every one of these had the broad support of the population and used guerrilla tactics. Many of them were very successful at a time, even seizing the area's that were struggling to be independent. Every one of them was completely destroyed.
And even when revolutions succeed, it's rarely a huge success. It took the Spanish 800 years to take back their country in the Reconquista and they used guerrilla tactics from very early on. By the time the American Revolution was complete, the economy was devastated and a sizable part of the population was dead or wounded. It took centuries for the Dutch to kick foreign powers out of the Lower Netherlands despite them becoming an economic superpower and the territory repeatedly changing hands.
The arc of history may bend towards freedom, but not every attempt succeeds.